The present invention describes an adaptive control system being preferably part of the portal, which provides a sophisticated method for a partial sequential and parallel invocation of portlets depending on the available resources and system utilization. Based on defined time mark for rendering content (maximum invocation time for displaying a portal page or a portal-wide portlets rending time mark), a number of available threads, and estimated invocation time for each portlet the inventive method determines and invokes a first group of portlets (80,90) providing the maximum number of portlets to be invoked sequentially without exceeding defined time mark for rending content, and then all remaining portlets (80,90) are to be invoked parallel to that first group of portlets. The invention guarantees reasonable response times and high scalability and performance. (FIG. 9).